R u sure ring piston job will require only 8K.....i had it done to my city 2008...just the ring replacement...not even pistons....only one of the rings was weak...at cylnder 2......so i had a ring replacement job...cost around 13K....4k is only the labour,,,,,as it requires a full day by the mechanic....3500 for a genuine head gasket....2200 for TP Ring....u can have the details from following thread......https://www.pakwheels.com/forums/engine-accessories/207345-engine-overhaul-required
and most importantly......It works...just as good as a swapd engine would do,.....im not in favour of having a swapd engine......u will have to change the engine number on ur registration book...which will ultimatly hurt ur reselling option......